AS MUCH as $100bn (£64.5bn) of investment is needed to bring the US power transmission system up to modern standards, US industry experts said this week.
The warning came after the country's worst ever blackout, affecting 50M people across the eastern States.
It is thought mechanical failure combined with human error could have caused the progressive shutdown.
'The issue in the US is underinvestment, ' said Luther Dow, director of power delivery at industry association the Electric Power Research Institute.
Generating capacity and customer demand for electricity in the US has dramatically outstripped transmission capacity.
'In the last decade there has been a 35% increase in load but the increase in transmission capacity has been only 18%, ' Dow stated.
Current investment plans show power generation capacity continuing to outgrow transmission capability at the same rate over the coming five years, he added.
Problems arise when separate parts of the transmission system are overwhelmed. When one route fails, power surges through alternative channels.
A study of the national transmission grid carried out by the US Department of Energy (DoE) in May last year also revealed that annual maintenance spending on the transmission network has fallen by £75.4M a year since 1975, to just over £1.29bn.
The sagging of a power line into trees was largely due to inadequate maintenance, said director at consultant PB Power, Sunil Talati.
Under-investment is against a backdrop of rapidly rising demand for electricity.
In the Eastern Interconnection zone (see diagram) 40% of transmission lines operate at their limit over half the time.
In its study the DoE noted that 'as customer demand in an area surpasses the import capability of the transmission lines serving that area, operators are forced to meet the area's demand with more expensive local generation rather than less expensive generation from somewhere else in the region'.
North America's electricity transmission infrastructure is fragmented. It is 73% privately owned, with federal and state owned public utilities operating the remaining 27%.
Historically there has been relatively little co-ordination between transmission firms.
This has resulted in weak links between geographical regions and variations in equipment and operating protocols, said director of academic body the Electric Power Institute, Ahmed Nafisi.
Transmission lines, substations, switches, circuit breakers and computers used to monitor and control power as it is transmitted are also out of date.
Parts of the power system are as much as 50 years old, said Dow.
Although modern, fourth generation IT control and safety systems exist, utilities companies usually still use first generation software, claimed PB Power senior vice president Bob Ballard.
Ballard and Talati put the bill for modernising transmission infrastructure at between £32.2bn and £64.5bn.
To achieve the necessary upgrade within this price bracket work should be carried out using conventional, tried and tested technology, they said.
Modernisation faces major hurdles in the form of planning - Americans already oppose construction of new high voltage pylons, forcing utilities to put cables in trenches at vastly greater cost.
INFOPLUS www. nceplus.co.uk/magazine